Radially extending composite structures

ABSTRACT

A composite structure having at least one radially extending part is provided. The composite structure is formed with ply layers. At least one of the ply layers used to form the radially extending part has fibers oriented at 17.5 to 27.5 degrees in relation to an edge of the ply layer.

BACKGROUND

In aerospace applications there is a need for light weight high strengthstructures. To meet these requirements fiber reinforced compositematerials are often used. Sometimes the structures include radiallyextending parts. Laying up plies of material in forming radiallyextending parts leads either to the formation of defects such aswrinkles, which weakens the part, or can not be achieved since the fibercannot be stretched radially. Darting can be used to lessen theformation of wrinkles and allow for radial changes, but darting itselfweakens the part. This invention provides a method of laying up fiberplies in a radially extending part without darting and without theformation of wrinkles or necessity of darts.

For the reasons stated above and for other reasons stated below whichwill become apparent to those skilled in the art upon reading andunderstanding the present specification, there is a need in the art foran improved radially extending composite structures.

SUMMARY OF INVENTION

The above-mentioned problems of current systems are addressed byembodiments of the present invention and will be understood by readingand studying the following specification. The following summary is madeby way of example and not by way of limitation. It is merely provided toaid the reader in understanding some of the aspects of the invention.

In one embodiment, a composite structure is provided. The compositestructure includes a radially extending part that is formed with plylayers. At least one of the ply layers used to form the radiallyextending part has fibers oriented at 17.5 to 27.5 degrees in relationto an edge of the ply layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more easily understood and furtheradvantages and uses thereof more readily apparent, when considered inview of the detailed description and the following figures in which:

FIG. 1 is a top view a radially extending part of one embodiment of thepresent invention;

FIGS. 2A and 2B are side perspective views of composite structureshaving radially extending parts of another embodiment of the presentinvention;

FIG. 3 is a side perspective view of a tool used to form compositestructures of an embodiment of the present invention;

FIGS. 4A, 4B, 4C and 4D illustrate possible fiber orientations ofembodiments of the present invention;

FIG. 5A is an illustration of patterned flags of one embodiment of thepresent invention;

FIG. 5B is an illustration of spliced flags of one embodiment of thepresent invention;

FIG. 5C is a close up view of a spliced area of FIG. 5B;

FIG. 5D is a top view of a produced layer of ply having a desired fiberorientation of one embodiment of the present invention;

FIG. 6 illustrates the orientation of fibers in adjacent ply layers ofone embodiment of the present invention;

FIG. 7 is an illustration of a forming head of an embodiment used toform ply layers;

FIG. 8 is a forming machine used to form composite structures of oneembodiment of the present invention; and

FIG. 9 illustrates a formation flow diagram of one embodiment of thepresent invention.

In accordance with common practice, the various described features arenot drawn to scale but are drawn to emphasize specific features relevantto the present invention. Reference characters denote like elementsthroughout Figures and text.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof, and in which is shownby way of illustration specific embodiments in which the inventions maybe practiced. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that changesmay be made without departing from the spirit and scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense, and the scope of the present invention isdefined only by the claims and equivalents thereof.

Embodiments of the present invention provide methods and apparatus forforming composite structures with radially extending parts without theneed for darting and without the formation of wrinkles that can weakenthe structure. In embodiments, plies of fiber having select orientationsare laid up one at a time. Materials used to form the compositestructures are generally described as ply layers. The ply layers can bemade of any materials with fibers (or plies) that exhibit desiredcharacteristics including but not limited to prepreg material and dryfiber material. The prepreg material and the dry fiber material caninclude, but is not limited to tapes, woven fabrics, non-woven fabricsand non-crimp fabrics. The orientation of the fibers (or plies) withinthe materials are described further below. Example orientations offibers in a ply layer are +22.5/−67.5 degrees or −22.5/+67.5 degrees. Infabric embodiments the fibers have at least two fiber orientations perlayer. That is, two sets of fibers with orientations that are typicallyorientated 90 degrees apart from each other are present in fabricembodiments. For example, fiber orientations in a fabric include 22.5and 112.5 degrees and −22.5 and 67.5 degrees. Due in part to variationsin formed ply layers, the above example orientation degrees can vary. Insome cases, the orientation degrees can vary up to 5 degrees or more. Ina tape embodiment, the fibers have only one fiber orientation.

Referring to FIG. 1, an example of a radially extending compositestructure 100 is provided. In particular, FIG. 1 illustrates a top viewof a radially extending composite structure 100. The composite structure100 in this example is annular shaped. As this example illustrates, thepart extends radially about a center point from an inner edge 103 to anouter edge 104 of the composite structure 100. FIGS. 2A and 2Billustrate further full circumference composite structures 200 and 202that include radially extending parts 204, 206, 208 and 210respectively. FIG. 3 illustrates an example of a tool 300 that can beused to form the full circumference composite structures 200 and 202.

As discussed above, embodiments use specific fiber orientations in theply layers. Examples of different orientations used in embodiments areprovided in FIGS. 4A, 4B, 4C and 4D. In particular, FIG. 4A illustratesa fiber orientation of 22.5 degrees. The 22.5 degrees is in relation toan edge of a ply layer that is further described below. The 0 degreeline represents the edge of the ply layer. FIG. 4B illustrates a −22.5degree orientation. The Fiber orientations illustrated in FIGS. 4A and4B would typically be used in ply layers prepreg and dry fiber tapes.FIG. 4C illustrates two orientations of fibers, 22.5 degrees and 112.5degrees. FIG. 4D also illustrates two orientations of fibers, −22.5degrees and 67.5 degrees. In particular, FIGS. 4C and 4D illustratefibers in a fabric that have two sets of fibers each 90 degrees apartform each other.

Typically a stock supply roll of fibers is provided by suppliers ineither a 90 degree orientation or a 0 degree orientation. However, theapplication of the 90 degree ply or 0 degree ply on radially extendingparts requires darting (cut out sections) to the radius of the part. Inembodiments of the present invention, ply rolls of material are madefrom the stock rolls to a desired orientation that does not requiredarting. Referring to FIG. 5A, patterned cut flags 502 of material thathave been pattern cut out of a supply roll to have a desired fiberorientation is illustrated. The patterned cut flags 502 having thedesired fiber orientation are then spliced together as illustrated inFIG. 5B. In one embodiment, the flags 502 are lined up with the endsoverlapping as illustrated in the close up view of area 504 which isillustrated in FIG. 5C. The amount of the overlap is a function of thedesign requirements. An example, overlap is 0.5 inches. This overlap insome designs ensures that the load in a given ply can be transferred inshear to an adjacent ply subject to the strength of the resin used.Splice locations are staggered when laying up plies on a tool so they donot overlap. In embodiments, where no overlap is desired, the flags 502are butt-spliced. In this embodiment, an additional ply can be added tothe layup to compensate for the discontinuous material. As long as thesplices are staggered, there is always the same number of continuousplies to carry the load. FIG. 5D is at top view of a ply layerillustrating a produced ply layer 500 having a fiber orientation of 22.5degrees. It will be understood, that lines 520 representing fibers areonly provided to illustrate the fiber orientation in relation to an edge522 of the ply layer 500. Fibers in an actual ply layer would berelatively close to each other.

In embodiments, composite structures are created by ply layers formed ona tool one ply at a time. In one embodiment, ply layers havingalternating fiber orientations are used to form the composite structure.For example, in one embodiment, alternating ply layers havingorientations of +22.5/−67.5 degrees and −22.5/+67.5 degrees are used toform the radially extending composite structures. An example ofalternating ply layers 602 and 604 having orientations of +22.5/−67.5degrees and −22.5/+67.5 degrees is illustrated in FIG. 6. One method ofapplying and forming ply layers on a tool is with a forming head 726 andautomatic ply feeder (dispensing device 724). An example of a forminghead 724 can be found in commonly assigned U.S. Pat. No. 7,513,769(Benson et al.) filed on Jul. 30, 2004, entitled “Apparatus and Methodsfor Forming Composite Stiffeners and Reinforcing Structures” which isherein incorporated by reference. In particular, FIG. 7 provides anexemplary example of a material dispensing device 724 and the forminghead 726. Material 740 (e.g., a ply layer or prepreg cloth) having thedesired fiber orientation is fed from a supply and tension roller 742and over a redirect roller 744 as motivated by a pair of feed rollers746. The material 740 passes beyond a cutting device 748 which may beused to cut the material to a specified length, width, or both such asdescribed hereinabove with respect to other embodiments of the presentinvention. The material 740 is then disposed onto a portion of a tool706A by a tack roller 750.

It is noted that the tack roller 750 (and subsequent rollers encounteredby the material 740) is shown in a first elevational view with a second,rotated elevational view depicted immediately therebeneath to provideadditional understanding of how the material 740 is being shaped by theinteraction of various rollers with the material 740 and the underlyingtool 706A.

The forming head 726 includes a plurality of rollers 728A-728D used toshape and debulk material 740 disposed over the tool 706A (or overpreviously shaped material plies disposed on the tool 706A). Thus, forexample, a first roller 728A engages the tool 706A to generally conformthe material 740 to the shape of the tool 706A. Second, a set of rollers728B may be used to press the material against the side walls 754 of thetool 706A. If desired, this may be accomplished with multiple sets ofrollers 728B working from the upper portion of the tool 706A to thebottom portion as depicted in the rotated elevational views of therollers 728B. Another set of rollers 728C may be used to press thematerial 740 into the interior lower corners 756 of the tool 706A. Asqueegee 758 (or shoe) may be used to help pull wrinkles from thematerial at one or more intermediate locations among the rollers728A-728D. Finally a set of rollers 728D may be used to press and formthe flange members of the composite structure 702.

It is noted that the process of forming the composite structure 702includes forming, shaping and debulking the material 740 from the insideout. In other words, the tack roller 750 applies pressure to the tool706A and material 740 disposed thereon at the center, with subsequentrollers 728A-728D each sequentially applying pressure at a locationfurther towards the outer edges of the material 740. Such a process hasbeen determined to be efficient and effective in removing wrinkles andair gaps between laminar plies of material thereby producing a highlyconsolidated and debulked composite member.

A take-up roller 760 may be associated with the forming head 726 (orindependently coupled with the carriage assembly 710) to collect carriermaterial 762 (also referred to as backing) which may be disposed on asurface of, for example, a prepreg material used to form the compositestructure 702. The carrier material 762, which may include a suitablepolymer material, not only keeps the prepreg material from adhering toitself when in rolled form (i.e., such as when on supply and tensionroller 742) but also may remain on the material 740 while the material740 is being shaped, formed and debulked so that the various rollers 750and 728A-728D do not stick to the material 740 or collect and build-upresin of a surface thereof. Additionally, the presence of such carriermaterial 762 may serve to protect the material 740 used to form acomposite structure 702 when the various rollers 728 press and rubagainst the material 740 during forming of the composite structure 702.

Another example of a forming head 804 used to form ply layers isillustrated in FIG. 8. Forming head 804 is part of a composite formingsystem disclosed in commonly assigned Patent Application No.______ ,entitled “Automated Composite Annular Structure Forming,” filed onevendate herewith which is incorporated in its entirety herein. FIG. 8illustrates a tool 800 that is mounted on a tool holding assembly 860that is in turn rotationally coupled to a tool holding support 861. Plylayers are applied then and formed on the tool 600 in this embodiment.As illustrated, the tool 800 rotates in relation to the tool holdingsupport 661 as the operator 612 applies the material (ply layer) 810 tothe tool 800. The forming head 604 that includes forming rollers formthe ply layer on the tool 800. Once, the ply layers have been formed,the forming head 804 is pulled back from the tool 800 via track 840. Thetool 800 with the formed ply layers 810 can then be removed for curingto form a composite structure. For example, tool 800 forms a compositestructure such as composite structures 200 and 202 in FIGS. 2 a and 2Bthat have radially extending parts 204, 206, 208 and 210 respectfully.Embodiments are not limited to specific cross-sectional geometries offormed composite structures. Any geometry that includes radiallyextending parts has application.

Referring to FIG. 9, a formation flow diagram 900 of a compositestructure of an embodiment is illustrated. As discussed above, theprocess starts by making a ply layer. This process involves cuttingflags from a stock supply having a desired orientation (902). The flagsare then lined up end to end (904) and spliced together (906) to formthe ply layer. The ply layer is then applied to a forming surface of atool or mandrel (910). The ply layer on the tool is then formed on theforming surface of the tool (912). It is then determined if more plylayers are required to form the composite structure (914). If more plylayers are required (914), a ply layer having a desired fiberorientation is selected (916). As discussed above, in some embodimentsit is desired to alternate the fiber orientations between adjacent plylayers. Once, the ply layer with the desired orientation has beenselected (916) it is applied to the forming surface of the forming toolat (910). Hence, ply layers are formed one at a time over each otheruntil a desired number of layers have been reached at (914). Once, it isdetermined the ply layering is complete at (914), the formed ply layerson the tool are then cured (918) to form the desired compositestructure.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement, which is calculated to achieve the same purpose,may be substituted for the specific embodiment shown. For example,slight variations in orientation of the fibers could be implemented withthe same result. Hence, variations of 5 degrees or more may be possible.This application is intended to cover any adaptations or variations ofthe present invention. Therefore, it is manifestly intended that thisinvention be limited only by the claims and the equivalents thereof.

1. A composite structure comprising: at least one radially extendingpart formed with ply layers, at least one of the ply layers used to formthe radially extending part having fibers oriented at 17.5 to 27.5degrees in relation to an edge of the ply layer.
 2. The compositestructure of claim 1, further comprising: at least one other ply layerhaving fibers orientated at −17.5 to −27.5 degrees in relation to theedge of the ply layer.
 3. The composite structure of claim 1, furthercomprising: at least one other ply layer having fibers orientated at62.5 to 72.5 degrees in relation to the edge of the ply layer.
 4. Thecomposite structure of claim 1, further comprising: at least one otherply layer having fibers orientated at −62.5 to −72.5 degrees in relationto the edge of the ply layer.
 5. The composite structure of claim 1,wherein the least one ply layer is made from a fabric having a first setof fibers and a second set of fibers, the first set of fibers and thesecond set of fibers having different orientations that are 90 degreesfrom each other.
 6. The composite structure of claim 5, wherein thefirst set of fibers have a fiber orientation of the 17.5 to 27.5 degreesand the second set of fibers have a fiber orientation of 107.5 to 117.5degrees.
 7. The composite structure of claim 6, further comprising atleast one other ply layer being a fabric having a third set of fibersand fourth set of fibers, the third set of fibers and the fourth set offibers having different orientations that are 90 degrees from eachother.
 8. The composite structure of claim 7, wherein the third set offibers have a fiber orientation of the −17.5 to −27.5 degrees and thefourth set of fibers have a fiber orientation of 62.5 to 72.5 degrees.9. A composite structure comprising: at least one radially extendingpart formed with material with fibers in at least one ply layer havingfirst fibers in generally a 22.5 degree fiber orientation in relation toan edge of the ply layer.
 10. The composite structure of claim 9,wherein the 22.5 degree orientation is generally a +22.5 degreeorientation.
 11. The composite structure of claim 9, wherein the 22.5degree orientation is generally a −22.5 degree orientation.
 12. Thecomposite structure of claim 9, wherein the at least one ply layer is aplurality of ply layers having alternating orientations of first fibersgenerally +22.5 degrees and generally −22.5 degrees.
 13. The compositestructure of claim 9, wherein the at least one ply layer is a fabriclayer also including second fibers in generally a 112.5 degree fiberorientation.
 14. The composite structure of claim 9, wherein the atleast one ply layer is a plurality of ply layers with adjacent plylayers having alternating fiber orientations.
 15. A method of forming acomposite structure having a radially extending portion, the methodcomprising: applying ply layers one at a time on a forming surface of atool configured to form a composite structure having at least oneradially extending part, wherein fibers in at least one ply layer areoriented 17.5 to 27.5 degrees in relation to an edge of the at least oneply layer; forming the ply layers on the forming surface of the tool;and curing the formed ply layers to form the composite structure. 16.The method of claim 15, wherein the fibers in at least one other plylayer are oriented −17.5 to −27.5 degrees in relation to an edge of theat least one other ply layer.
 17. The method of claim 15, wherein thefibers in at least one other ply layer are oriented 62.5 to 72.5 degreesin relation to an edge of the at least one other ply layer.
 18. Themethod of claim 15, wherein the fibers in at least one other ply layerare oriented −62.5 to −72.5 degrees in relation to an edge of the atleast one other ply layer.
 19. The method of claim 15, wherein the fiberorientation of alternating ply layers is 90 degrees apart from eachother.
 20. The method of claim 15, wherein at least one ply layer is afirst fabric layer having a first set of fibers and a second set offibers, the first set of fibers having the
 17. 5 to 27.5 degreeorientation and the second set of fibers having a 107.5 to 117.5 degreeorientation.
 21. The method of claim 20, wherein another ply layer is asecond fabric layer having a third set of fibers and a fourth set offibers, the fourth set of fibers having a −17.5 to −27.5 degreeorientation and the fourth set of fibers having a 62.5 to 72.5 degreeorientation.
 22. The method of claim 15, further comprising: producingmaterial for a ply layer having fibers at a select orientation inrelation to an edge of the ply layer.
 23. The method of claim 22,wherein producing the material, further comprises: pattern cutting flagsfrom a stock supply of material to achieve a desired fiber orientation;placing the flags end to end; and splicing the flags together to form aply layer having the select fiber orientation.
 24. The method of claim23, further comprising: overlapping ends of the flags when splicingtogether.
 25. The method of claim 15, wherein applying the ply layers tothe tool further comprising: applying the ply layer to the formingsurface of the tool so that the spliced ends of adjacent ply layers donot align.
 26. A composite structure comprising: at least one radiallyextending part formed with ply layers, at least one of the ply layersused to form the radially extending part having fibers oriented at 62.5to 72.5 degrees in relation to an edge of the ply layer.